Numerous items such as smart phones, smart watches, tablets, automobiles, aerial drones, appliances, aircraft, exercise aids, and game controllers may utilize motion sensors during their operation. In many applications, various types of motion sensors such as accelerometers and gyroscopes may be analyzed independently or together in order to determine varied information for particular applications. For example, gyroscopes and accelerometers may be used in gaming applications (e.g., smart phones or game controllers) to capture complex movements by a user, drones and other aircraft may determine orientation based on gyroscope measurements (e.g., roll, pitch, and yaw), and vehicles may utilize measurements for determining direction (e.g., for dead reckoning) and safety (e.g., to recognizing skid or roll-over conditions).
Many sensors such as accelerometers, gyroscopes, pressure sensors, and microphones are implemented as microelectromechanical systems (MEMS) sensors. Micromechanical components of the sensor are fashioned using silicon fabrication techniques, and those micromechanical components respond (e.g., move) in response to certain external stimuli that are measured by the sensor, based on the design of the particular micromechanical components. The response of the micromechanical component to the external stimuli may be measured, e.g., by measuring the relative distance between the moving micromechanical components and fixed components of the sensor.
In the case of a MEMS gyroscope, certain micromechanical components are caused to vibrate at a drive frequency. A number of components are often physically connected by numerous springs, each of which is designed to enable motion in certain directions while restricting movement in other directions. When a mass that is vibrating at the drive frequency experiences a Coriolis force along an axis that is perpendicular to the drive axis as a result of rotation, it will move along this Coriolis axis (e.g., a “sense” or “Coriolis” axis) if springs or other structural features do not prevent such a motion. This Coriolis force is proportional to the angular velocity of the rotation. This motion may then be sensed based on the motion of the mass (or in some applications, an additional proof mass connected by the additional springs) in the sense direction, e.g., based on the relative distance between the moving sense mass and fixed components of the gyroscope.
A MEMS gyroscope is implemented in devices that may experience numerous other forces in addition to angular velocity. For example, the gyroscope may also experience forces due to linear acceleration and angular acceleration. These forces may be imparted on the components of the MEMS gyroscope such as the drive and proof masses, resulting in movements that are improperly interpreted as resulting from a Coriolis force or modifying the movement due to the Coriolis force.